Nope, that won't work. Not because of direct compatibility issues (although I can definitely picture a larger oscar snacking down on a smallish dragon goby) but because they have different water parameter requirements. The goby needs hard, brackish water while the oscar needs pure freshwater.

Good tankmates would be other brackish gobies like knight gobies, "freshwater" flounder, archers, monos, scats and chromides.

Gobies are usually mostly all right with other goby type fish. They're sometimes pretty shy. And yeah they're brackish too. Dragon gobies sometimes will get "slimy" looking if they're kept in freshwater forever.

my dragon goby got along great with my 2 african ropefish, they would play together and sleep together.I also have 2 angle fish and a rapheal catfish and all got along great.I keep my tank low level brackish and all of my fish THRIVE! just be sure not to put dragons with aggressive fish as they will not survive. Since they are so peacful and will not fight for their food one of the most common causes of death in dragon gobies is malnurishment, to avoid this problem simply feed them their blood worms with a turkey baster or your hand, it works great and creates a special bond(they will get all excited to see you and greet you everyday!) just be careful not to overfeed them as they will make themselves sick! I found that in very young dragons everyother day is perfect and once their grothw slows in maturity go down to twice a week:)
Hope I was able to help!

Most is a misconception My dragon Goby, He lives with Ghost Shrimp, A Frog, some goldfish, a loach, danios and minnows. and a couple plecos, everyone is healthy and happy. it just depends on what the water is set to. from my understandings. and the goby is about 10 inches.